Recently, prevalent portable wireless communication apparatuses have required fast throughput, and a Phase Locked Loop (PLL) circuit operating at a high frequency band has been required as a frequency synthesizer in wireless communication.
The PLL circuit includes a frequency divider which frequency-divides a high frequency band signal to a low frequency band signal. An injection locked frequency divider (ILFD) capable of high speed operation at a high frequency band of 10 GHz or more using low power consumption is used as a frequency divider.